Serum/plasma separator {13 {0 cannula fluid by-pass type

ABSTRACT

A self-contained fluid separator assembly capable of separating blood into its component parts of plasma or serum, the light phase, and cellular portion, the heavy phase, is disclosed. The assembly comprises a container having a first open end for receiving blood for subsequent separation and a second open end for removing separated light phase; and closures sealing the open ends of the container, the closures being formed of a selfsealing elastomeric material which is penetrable by a cannula. A piston responsive to centrifugal force is slidably disposed within the container, having its lateral surfaces in sealing contact with the inner surfaces of the container. The piston divides the chamber defined by the container into upper and lower compartments. In its initial position within the container, the piston is in cooperation with a conduit means sealed by a seal means responsive to centrifugal force. The assembly is operated by first filling the lower chamber with blood to be separated. Separation is carried out at relatively low centrifugal speeds. Following separation, the centrifugal speed is increased, removing the conduit seal to establish communication between upper and lower compartments. Pressure of the descending piston forces the light phase blood component through the conduit and into the upper chamber where it is isolated. When the piston reaches a predetermined position, continued cooperation between piston and conduit terminates, closing the communication between upper and lower chambers. With communication terminated, the incompressibility of the contents of the lower chamber prevent further descent of the piston. Centrifugal force may then be terminated, leaving the blood specimen separated into light and heavy phases which are permanently isolated from each other by the now impermeable piston.

June 3, 1975 SERUM/PLASMA SEPARATOR CANNULA FLUID BY-PASS TYPE [75]Inventor: Waldemar A. Ayres, Rutherford,

NJ. [73] Assignee: Becton, Dickinson and Company,

East Rutherford, NJ.

[22] Filed: Feb. 27, 1974 [21] Appl. No.: 446,384

[52] US. Cl. 210/130; 210/516; 2l0/DIG. 23; 2l0/DIG. 24 [51] Int. ClB0ld 21/26 [58] Field of Search 23/230 B, 258.5, 259, 292; 128/2 F, 214R, 218 M, 272; 210/83, 84, 131, 359, 514-518, DIG. 23, DIG. 24, 130;233/1 A, l R, 26

[56] References Cited UNITED STATES PATENTS 2,305,278 12/1942 Smith128/218 M 2,313,483 3/1943 Smith 128/218 M 2,869,543 l/1959 Ratcliff etal. 128/218 M 3,706,305 12/1972 Berger et al. 210/DlG. 24

Primary ExaminerCharles N. Hart Assistant Examiner--Robert G. MukaiAttorney, Agent, or Firml(ane, Dalsimer, Kane, Sullivan and Kurucz [5 7ABSTRACT A self-contained fluid separator assembly capable of separatingblood into its component parts of plasma or serum, the light phase, andcellular portion, the heavy phase, is disclosed. The assembly comprisesa container having a first open end for receiving blood for subsequentseparation and a second open end for removing separated light phase; andclosures sealing the open ends of the container, the closures beingformed of a self-sealing elastomeric material which is penetrable by acannula. A piston responsive to centrifugal force is slidably disposedwithin the container, having its lateral surfaces in sealing contactwith the inner surfaces of the container. The piston divides the chamberdefined by the container into upper and lower compartments. In itsinitial position within the container, the piston is in cooperation witha conduit means sealed by a seal means responsive to centrifugal force.

The assembly is operated by first filling the lower chamber with bloodto be'separated. Separation is carried out at relatively low centrifugalspeeds. Following separation, the centrifugal speed is increased,removing the conduit seal to establish communication between upper andlower compartments. Pressure of the descending piston forces the lightphase blood component through the conduit and into the upper chamberwhere it is isolated. When the piston reaches a predetermined position,continued cooperation between piston and conduit terminates, closing thecommunication between upper and lower chambers. With communicationterminated, the incompressibility of the contents of the lower chamberprevent further descent of the piston. Centrifugal force may then beterminated, leaving the blood specimen separated into light and heavyphases which are permanently isolated from each other by the nowimpermeable piston.

3 Claims, 2-Drawing Figures SERUM/PLASMA SEPARATOR CANNULA FLUID BY-PASSTYPE BACKGROUND OF THE INVENTION 1. Field of the Invention i Theinvention concerns an assembly for the separation and isolation of bloodplasma and blood serum from blood.

2. Brief Description of-the Prior Art It is known to separate blood intoits component parts by centrifugation, particularly employing a sealedcontainer suchas I is disclosed in US. Pat. No. 2,460,641. This patentdiscloses a container having a closure at its open end which is capableof being penetrated by a cannula through which blood passes into thecontainer. Clinical laboratories have heretofore used this device tocollect a blood sample for subsequenttioned initially adjacent thestopper for closing the container. After the blood to be separated is inthe container the assembly is centrifuged. After the blood is separated,increased centrifugal force is applied to the container, the sealbetween the inner surface of the container and piston is broken and thepiston is deformed, moving down through the light phase with the lightphase passing solely around thelateral surfaces of the piston and theinner surfaces of the container. When the piston reaches the interfacebetween the light phase and the heavy phase, the piston movement isstopped, the force is terminated, and the seal is reestablished betweenthe inner surface of the container and the resilient piston to present abarrier between the two phases.

Disclosed in my US. Pat. No. 3,779,383 is a serum/- plasma separatoras'compared with which the present apparatus of my invention utilizescertain different principles and construction elements. 7

Other devices known to the artare generally the filtration devices whichseparate blood into its compo nent phases such as those disclosed-in US.Pat. Nos. 3,481,477 and 3,512,940.

SUMMARYOF THE INVENTION The invention comprises: a self-contained fluidseparator assembly capable of separating blood into its component partsof plasma or serum and cellular part comprising (a) a container having afirst open end which is adapted to receive blood for subsequentseparation into a light phase and a heavy phase and a second openend'for removing the separated light phase; (b) closures sealing theopen ends of the container, the closures being formed of a self-sealingelastomeric ma terial which is penetrable by a cannula; (c) a pistonslidably mounted in said container, having a specific gravity greaterthan the cellular portion-of the blood to be separated and having meanson' an outer surface in sealing engagement with an inner surface of thecontainer; said piston being disposed in said container so as toseparate said chamber into upper and lower compartments; said pistonbeing initially mounted in said container at a position adjacent to saidsecond end and being movable by centrifugal force to a second positionwithin saidcontainer, whereby said upper chamber is expanded in volumeand said lower chamber is reduced in volume; a tube having one end fixedto the closure for said second end and one end free, terminating withinthe chamber defined by said container, said tube having an opening intosaid chamber at the terminal free end and an opening into said chamberat the fixed end; seal means closing said opening at the terminal, freeend of said tube, said means being removable by centrifugal force; saidpiston in its initial position cooperating with said tube, whereby saidtube forms a conduit through said piston, communicating with said upperand lower compartments, said piston in its second position being removedfrom cooperation with said tube, whereby said conduit is terminated.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a cross-sectional sideelevation of a separator assembly of the invention illustrating acannula penetrating one of the closures through which blood isintroduced into the container prior to separation.

FIG. 2 is a'view similiar to FIG. 1 illustrating the separation of theblood into the light phase and heavy phase with the piston separatingthe two phases.

DETAILED DESCRIPTION OF THE INVENTION For a better understanding of theinvention, a description of the drawings of the illustrative embodimentsis had, particularly with respect to the embodiments shown in FIGS. 1and 2.

Referring to FIG. 1, it is seen that the separator assembly 10 comprisesa tubular member or container 12 having mounted in each open end 11, 15closures 14 and 16. Closures 14 and 16 are made of a self-sealingelastomeric material such as rubber which are capable of receivingcannula 18 penetrated therethrough as illustrated in FIG. 1, forconducting blood 5 into the container. When the cannular is removed theclosure is resealed with no loss of blood 5 passing through thepenetration portion 31 as illustrated in FIG. 2.

Closure 14 is formed having a depending cylindrical bodyportion 20 and aflanged head portion 22 integrally formed therewith. Body portion 20 hasa diameter slightly greater than the internal diameter of the container12 so that closure 14 when mounted into end 11 provides a pressure fitto seal the end. Head portion 22 is preferably shaped in the form of ahexagon and is slightly greater in diameter than body portion 20 whichpermits the assembly to be positioned on its side without danger ofrolling. An upper axial recess 24 is provided for easy access throughstopper 16 which reduces the force required to penetrate with cannula18. A lower annular recess 21 is provided in the bottom surface 19 ofclosure 14 for receiving an initial flow of separated blood plasma orserum as hereinafter described in greater detail. The recess 21 is inopen communication with upper compartment 45 which is defined 'by thecontainer walls 13, closure 14 and the upper surface 41 of piston 40.

Stopper 16 is formed preferably of the same material as'stopper'14.Stopper 16 has a cylindrical body portion 28 and an integrally formedhead portion 30 having an outer axial recess 24. Body portion 28 has aninner annular recess 29 to provide a self-sealing penetrable zone 31 tofacilitate insertion of cannula 18 with minimum force while maintaininga sealed closure. As noted above, stopper or closure 14 as well as 16 isinserted into ends 11 and 15 respectively in compression to maintainends 11 and 15 of container 12 in sealed engagement.

Container 12 is formed preferably of glass but a suitable plasticmaterial may be employed. Intermediate ends 11 and 15 of container 12 ispiston 40 which moves from the initial starting position illustrated inFIG. 1 under centrifugal force to the terminal position after theseparation of the light phase from the heavy phase, as shown in FIG. 2.The piston comes to rest slightly above the interface 4 between theseparated lighter phase 5a and heavier phase 5b of the separated blood 5as will be hereinafter described. It is necessary to have a piston 40possessing a specific gravity exceeding the specific gravity of blood.Further, the piston 40 component of the invention herein does notdeform; that is, the seal of the piston 40 with respect to the innersurface 13 of the container 12 is constantly maintained throughout itstravel from its initial position of FIG. 1 to its terminal position ofFIG. 2.

Piston 40 includes a tubular metal insert 52 which is mounted in annularrecess 54 of piston 40. Metal insert 52 is preferably made of stainlesssteel or other rigid, chemically inert material having a specificgravity greater than blood. Piston 40 is formed of elastomeric materialand is provided with annular recess 54 which is dimensioned to receivetubular member 52 in an interference fit so that no air space remains inannular recess 54.

The elastomeric portion of piston 40 comprises an outer wall 48 andspaced therefrom is inner wall 46 which defines annular recess 54.Formed integrally with wall 48 are a plurality of axially spaced sealingrings 50 which contact the inner wall surface 13 of container 12 insealing engagement. Piston 40 when mounted in container 12 will maintainsealing contact with inner wall 13 of container 12 throughout its pathof travel within container 12. During the centrifuging operationhereinafter described, piston 40 is subjected to centrifugal forceswhich start the descent of the piston and this action establishes apressure differential on the top and bottom surfaces of diaphragm 44.Diaphragm 44 has a relatively small thickness and lies adjacent stopper14 in its initial position as seen in FIG. 1, with a small space 45separating piston 40 from closure Piercing diaphragm 44 of piston 40 andthereby traversing the body of piston 40 from lower end 86 to upper end41 is tube 80 having openings 82, 84. Tube 80 is rigidly fixed inposition to closure 14 at a point adjacent to opening 84. Upper opening84 comunicates with recess 21 and opening 82 at the lower end of tube 80would communicate with chamber 3 of container 12 if it were not sealedwith centrifugal seal 90 as shown in FIG. 1.

To operate the separator asesmbly of the invention, it is preferred thatthe assembly be first evacuated of air so that when cannula 18penetrates closure 16 blood will fill the lower chamber 3 of container12 without requiring the use of an air vent.

After cannula 18 is withdrawn and chamber 3 of container 12 is filledwith blood 5 the assembly 10 is placed in a centrifuge and the blood isseparated employing relatively low centrifugal forces which do not causethe seal or 40 to move from their initial positions. At this low speedcentrifugation, the light phase is separated from the heavier phase ofthe blood 5. Thereafter the rotational speed of the centrifuge isincreased. Then, centrifugal seal 90, having an interference fit withthe end of tube 80 is spun off by the centrifugal force, and falls tothe bottom of container 12, as shown in FIG. 2, leaving opening 82 ofcannula 80 open. The opening of cannula 80 provides an outlet for thelight phase 5a to travel upward and exit from opening 84 of tube 80 intorecess 21. This removal of liquid permits piston 40 to descend furtherin light phase 50 forcing additional light phase 5a to travel throughtube 80 and into recess 21 which communicates with the expanding chamber45. When piston 40 approaches the end of tube 80 and slides off thelower end of tube 80, the selfsealing nature of the highly resilientelastomeric diaphragm 44 closes the opening formed when tube 80 pierceddiaphragm 44. Withpiston 40 now disassociated from tube 80 asillustrated in FIG. 2, the conduit between upper chamber 45 and lowerchamber 3 is closed. The blood phases being incompressible, piston 40cannot descend farther and thereby stops slightly above the interfacebetween the separated blood phases as shown in FIG. 2. In this locationpiston 40 forms an impervious barrier between the now separate andisolated blood phases. During its descent, piston 40 maintained sealingengagement with inner wall 13 of container 12. Thus, there is a completeseal and isolation of the component phases of the blood, which will notremix.

One skilled in the art will readily observe that by predetermining thelength of tube 80 one can predetermine the location where piston 40 willcome to rest.

In an optional embodiment of the invention as shown in FIGS. 1 and 2 afilter element may fill the recess 21 within closure 14, as shown inFIG. 2. Thus, by insertion of a filter element in the flow path of lightphase 5a it is possible to simultaneously filter the light phase whileit is being isolated from the heavy phase of the blood.

What is claimed is:

1. A self-contained fluid separator assembly capable of separating bloodinto its component parts of light phase plasma or serum, and heavy phasecellular material, comprising:

a container having a first open end which is adapted to receive bloodfor subsequent separation into a light phase and a heavy phase and asecond open end for removing the separated light phase;

closures sealing the open ends of the container, the closures beingformed of a self-sealing elastomeric material which is penetrable by acannula;

a piston slidably mounted in said container having a specific gravitygreater than the specific gravity of the blood and having means on anouter surface in sealing engagement with an inner surface of thecontainer, said piston having a diaphragm portion forming partial upperand lower surfaces of said piston, said diaphragm portion being of aselfsealing elastomeric material penetrable by a cannula; said pistonbeing disposed in said container so as to separate the chamber definedby said container with said closures, into upper and lower compartments;

said piston being initially mounted in said container at a positionadjacent to said second end and being constructed and arranged ,to moveat a predetermined centrifugal force to a second position within saidcontainer, whereby said upper compartment is expanded in volume and saidlower compartment is reduced in volume;

a tube of pre-determined length having one end fixed to the closure forsaid second end and one end free, terminating within said chamber, saidtube having an opening into said chamber at the terminal free end and anopening into said upper compartment at the fixed end;

seal means closing said opening at the terminal, free end of said tube,said seal means being constructed and arranged to disengage from saidtube at said predetermined centrifugal force;

said piston in its initial position cooperating with said tube, so thatsaid tube pierces the diaphragm portion of said piston, whereby saidtube together with said seal means forms a closed conduit through saidpiston, and whereby upon disengaging of said seal means by centrifugalforce, communication between said upper and lower compartments isestablished, said piston in its second position being removed fromcooperation with said tube, whereby said conduit is terminated and thediaphragm portion of said piston previously pierced by said tube isself-sealed.

2. The self-contained fluid separator of claim I wherein the pistonincludes a rigid tubular sleeve mounted in a generally tubular outerbody portion formed of rubber and having at least one sealing ring onits outer portion for sealing engagement with the inner wall of thecontainer.

3. The piston of claim 1 wherein a tubular metal sleeve is mounted insealing engagement in a complementary annular recess formed in a rubberbody portion having an interference fit so that substantially no airspace is provided between the walls defining the annular recess and theinner and outer walls of the rigid tubular member.

1. A self-contained fluid separator assembly capable of separating bloodinto its component parts of light phase plasma or serum, and heavy phasecellular material, comprising: a container having a first open end whichis adapted to receive blood for subsequent separation into a light phaseand a heavy phase and a second open end for removing the separated lightphase; closures sealing the open ends of the container, the closuresbeing formed of a self-sealing elastomeric material which is penetrableby a cannula; a piston slidably mounted in said container having aspecific gravity greater than the specific gravity of the blood andhaving means on an outer surface in sealing engagement with an innersurface of the container, said piston having a diaphragm portion formingpartial upper and lower surfaces of said piston, said diaphragm portionbeing of a self-sealing elastomeric material penetrable by a cannula;said piston being disposed in said container so as to separate thechamber defined by said container with said closures, into upper andlower comparTments; said piston being initially mounted in saidcontainer at a position adjacent to said second end and beingconstructed and arranged to move at a predetermined centrifugal force toa second position within said container, whereby said upper compartmentis expanded in volume and said lower compartment is reduced in volume; atube of pre-determined length having one end fixed to the closure forsaid second end and one end free, terminating within said chamber, saidtube having an opening into said chamber at the terminal free end and anopening into said upper compartment at the fixed end; seal means closingsaid opening at the terminal, free end of said tube, said seal meansbeing constructed and arranged to disengage from said tube at saidpredetermined centrifugal force; said piston in its initial positioncooperating with said tube, so that said tube pierces the diaphragmportion of said piston, whereby said tube together with said seal meansforms a closed conduit through said piston, and whereby upon disengagingof said seal means by centrifugal force, communication between saidupper and lower compartments is established, said piston in its secondposition being removed from cooperation with said tube, whereby saidconduit is terminated and the diaphragm portion of said pistonpreviously pierced by said tube is self-sealed.
 1. A self-containedfluid separator assembly capable of separating blood into its componentparts of light phase plasma or serum, and heavy phase cellular material,comprising: a container having a first open end which is adapted toreceive blood for subsequent separation into a light phase and a heavyphase and a second open end for removing the separated light phase;closures sealing the open ends of the container, the closures beingformed of a self-sealing elastomeric material which is penetrable by acannula; a piston slidably mounted in said container having a specificgravity greater than the specific gravity of the blood and having meanson an outer surface in sealing engagement with an inner surface of thecontainer, said piston having a diaphragm portion forming partial upperand lower surfaces of said piston, said diaphragm portion being of aself-sealing elastomeric material penetrable by a cannula; said pistonbeing disposed in said container so as to separate the chamber definedby said container with said closures, into upper and lower comparTments;said piston being initially mounted in said container at a positionadjacent to said second end and being constructed and arranged to moveat a predetermined centrifugal force to a second position within saidcontainer, whereby said upper compartment is expanded in volume and saidlower compartment is reduced in volume; a tube of pre-determined lengthhaving one end fixed to the closure for said second end and one endfree, terminating within said chamber, said tube having an opening intosaid chamber at the terminal free end and an opening into said uppercompartment at the fixed end; seal means closing said opening at theterminal, free end of said tube, said seal means being constructed andarranged to disengage from said tube at said predetermined centrifugalforce; said piston in its initial position cooperating with said tube,so that said tube pierces the diaphragm portion of said piston, wherebysaid tube together with said seal means forms a closed conduit throughsaid piston, and whereby upon disengaging of said seal means bycentrifugal force, communication between said upper and lowercompartments is established, said piston in its second position beingremoved from cooperation with said tube, whereby said conduit isterminated and the diaphragm portion of said piston previously piercedby said tube is selfsealed.
 2. The self-contained fluid separator ofclaim 1 wherein the piston includes a rigid tubular sleeve mounted in agenerally tubular outer body portion formed of rubber and having atleast one sealing ring on its outer portion for sealing engagement withthe inner wall of the container.